The present invention relates to a waveguide variable power divider/combiner, and more particularly to a continuously variable power divider/combiner having a differential phase shifter.
Communication satellites employ power dividers/combiners for a variety of applications. For example, communication satellite systems require that the antenna provide a number of separate beams operating on the same frequency. The antenna must be capable of switching, or reconfiguring, the beams to accommodate changing traffic patterns. Power dividers/combiners are used to provide this much-needed flexibility in the antenna system.
Typically, waveguide variable power dividers/combiners are comprised of two orthomode transducers with a movable, or rotating phase shifter therebetween.
There are several variations of variable power divider/combiners, including a spiral septum mounted on a rotatable shaft wherein rotation of the shaft moves the septum in such a way so as to change the resonant frequency. Also known, is a rotary joint that orients a flexible septum positioned within a hollow waveguide. The rotary joint positions various system components with respect to each other with a minimum of waste space to apply energy to, or derive energy from, an antenna structure.
Another known variable power divider/combiner is a series of rectangular waveguides that are manually rotatable relative to one another to create a rotated wave. Also known, is a variable power divider having first and second orthomode transducers coupled together by a hollow waveguide having a spiral plate rotator therebetween.
The moving parts required by the phase shifter in all of these examples introduce the need for mechanical parts, i.e. motors, actuators, gears, bearings, choke joints, etc., which are prone to component failure and malfunction. Also, the motors, actuators, gears, etc. are relatively heavy and sizable. In addition, the inertial mass must be accelerated for switching. As a result, the switching speed is limited by the inertial mass.
Prior art non-mechanical power divider/combiner technologies are known. However, there are significant drawbacks associated with the known non-mechanical devices. For example, known devices may be capable of shifting the phase of an incoming signal without the need for moving parts, but cannot combine different signals sources or divide a single incoming signal into more than one outgoing source.
The present invention is a waveguide variable power divider/combiner that has no mechanically moving parts. The present invention has two septum polarizers with a ferrite differential phase shifter therebetween. Changing the bias magnetic field, H, in the ferrites controls the differential phase between two spatially orthogonal modes. Each septum polarizer has two ports that can be designated as input and output ports.
Depending on the differential phase in the ferrite section, the input power can be split between two output ports in any ratio. The ratio of the output signals is continuously variable between zero and infinity. With two input signals of a predetermined frequency and appropriate phase, the power divider/combiner of the present invention will combine both signals and make the combined signal accessible at one or the other of two output ports.
It is an advantage of the present invention that no mechanical actuators are needed. The present invention is lighter than prior art devices making it suitable for any spacecraft application in any frequency band. Additionally, the present invention is suitable for radar as well.
It is an object of the present invention to provide a waveguide variable power divider/combiner that has no movable parts. It is another object of the present invention to control the differential phase by changing the bias magnetic field in a ferrite differential phase shifter.
It is a further object of the present invention to provide a ratio of output signals that is continuously variable between zero and infinity. It is still a further object of the present invention to reduce the size and weight of a power divider/combiner, while improving the switching speed.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.